This invention relates to devices to heat hydrocarbon fuel in the fuel feed line to an internal combustion engine between the fuel pump and the carburetor and refers more particularlly to such devices wherein the source of heat is water from the coolant system of the internal combustion engine, typically taken from the bleed line to the vehicle body heater after the heater and before the water pump.
It is well known that heating gasoline fuel (or any hydrocarbon fuel) substantially changes the volume of the fuel and, thus, when the fuel is relatively heated with respect to the fuel temperature in the gas tank, improved mileage is obtained. Yet further, improved function of various sorts in internal combustion engines occurs when the fuel is relatively heated before passage into the cylinders for ignition, Known effects include cleaner combustion (more complete combustion with less pollution products resulting) and smoother engine operation (less ping and knock). The relative increase in temperature in the fuel aids vaporization in the carburetor. These and various other advantages are well documented in the prior art, particularly including the citations made herebelow.
There are, generally speaking, three possible sources of heat for fuel preheating, typically, the engine exhaust gases, the hot oil in the crankcase and the hot water in the radiator and engine jacket which is also conventionally employed to power the vehicle body heater of a truck or automobile. Experience has demonstrated that the latter source of heat is by far the safest and most useful. The extreme temperature of the exhaust gases, for example, introduce a hazard as well as material and wear factor which has proved this concept not satisfactory. Access to the oil in the crank case is far less convenient, as well, than to the water/antifreeze coolant which circulates in the heater circuit, typically from an engine block connection to the heater and then to the water pump in conveniently available fashion. If a heater is not present in the circuit external of the engine from the block water jacket to the pump (very unusual) the takeoff of hot water is anywhere on this line. Some water recycle lines go directly to the radiator.
One great difficulty of any useful, commercial fuel preheater system is the complexity and vulnerability of the heat exchanger on the gas line and the water flow lines and connections into and from said sleeve exchanger. When a fuel heat exchanging system employing engine cooling water is employed as is seen in some of the prior art cited here below, the typical flow system includes one T connector in a first portion of the heater circuit, which flows hot water through a flexible line to a first connection on the gas line sleeve. The output from the gas line sleeve then involves a separate connection and flexible line leading to yet another T connection in the heater line. Each one of the junctions for this hot water bypass to the exchanger on the gas feed line is vulnerable to leakage or breakage, as well as connecting line failures. Yet further, in the crowded engine compartment, particularly in the closely packed, space-precious engine compartment of the present day, the multiplicity of lines and connections is very undesirable. Installation thereof is complex and difficult, often in difficulty accessible portions of the engine compartment and accessibility for inspection, replacement and repair is not optimum. Yet further, costs of construction, installation, maintenance and repair of such systems are excessive and the susceptibility of such system to break down or failure (with concomitant failure of the engine cooling system) have caused such proposed systems, well known to the art, to remain hypothetical and theoretical, rather than effective fuel savers and engine function optimizers.
Accordingly, what is needed and desired is a simplified, effective, cheap, dependable gasoline fuel preheater system which can be readily installed and which will function safely over a long interval of time without failure. This is the purpose of the subject invention.